Author ORCID Identifier

https://orcid.org/0000-0002-4469-3318

Year of Publication

2021

Degree Name

Doctor of Philosophy (PhD)

Document Type

Doctoral Dissertation

College

Agriculture, Food and Environment

Department

Plant and Soil Sciences

First Advisor

Dr. David Van Sanford

Abstract

Fusarium head blight (FHB) of wheat (Triticum aestivum L.) results in discolored grain contaminated with deoxynivalenol (DON). DON accumulation, an indicator of FHB resistance, can be quantified and used as the basis for direct phenotypic selection, but testing is expensive. The primary objective of this study was to evaluate an optical seed sorter as an alternative to DON testing for FHB resistance breeding. Three hundred F4 derived soft red winter wheat (SRWW) breeding lines were grown in an inoculated FHB nursery over several years in Lexington, KY. Grain from each breeding line was sorted using an optical seed sorter calibrated to reject scabby (discolored) and accept non-scabby kernels. The percentage of fusarium damaged kernels estimated with the optical sorter (FDKos) was recorded for each breeding line, and accepted seed was used to plant subsequent generations. DON was lowered each cycle of optical sorter-based selection (lines with low FDKos were selected). Breeding lines were genotyped at loci on chromosomes 3BS, 2DL, and 5A using the following DNA markers: TaHRC, CFD233, and GWM304. Each cycle of optical sorter-based selection increased the percentage of lines with the resistant genotype at TaHRC. In other words, the sorter selected lines with Fhb1, a major effect FHB resistance QTL. Optical sorter-based selection also enhanced FHB resistance in several different marker genotype combinations. To evaluate optical sorter-augmented genomic selection (OSA-GS) for lower DON accumulation, six hundred thirty-eight University of Kentucky (UKY) breeding lines were genotyped using genotyping-by-sequencing (GBS) and grown in the FHB nursery. One hundred twenty of the F4 derived lines were also genotyped using GBS. FDKos data from the 120 F4 derived lines was used to train a genomic prediction model. Genomic estimated breeding values (GEBVs) for FDKos were computed for the UKY lines, then lines were selected based on FDKos GEBVs. OSA-GS lowered DON; moreover, using previously published cost estimates for the price of an optical sorter, DON analysis, and GBS, we determined that OSA-GS required less financial investment than direct phenotypic selection. Taken together, our findings indicate that the optical seed sorter has efficacy as a tool for FHB resistance breeding in SRWW.

Digital Object Identifier (DOI)

https://doi.org/10.13023/etd.2021.026

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